The bacteriological quality of smoked game meat in Lubumbashi has not been studied much to date. The present study focused on the analysis of 182 samples of smoked game meat from three species, Syncerus ... [more ▼]

The bacteriological quality of smoked game meat in Lubumbashi has not been studied much to date. The present study focused on the analysis of 182 samples of smoked game meat from three species, Syncerus caffer (n = 63), Phacochoerus aethiopicus (n = 60) and Sylvicapra grimmia (n = 59), sold at retail outlets in Lubumbashi. The isolation of Escherichia coli from 81.3% of samples (mean 4.87 ± 0.6 log10 CFU.g-1 of sample) confirms significant faecal contamination of smoked game meat. The study has determined by culture prevalences of 0.0%, 4.3% [CI95% 1.4-7.4], 3.8% [CI95% 1.1-6.6] and 14.2% [CI95% 9.2-19.4] respectively for Shiga toxigenic Escherichia coli (STEC), Salmonella spp., Campylobacter jejuni and Campylobacter coli. Using Polymerase Chain Reaction, these prevalences were of 2.2% [IC95% 0.1-4.3], 6.0% [IC95% 2.6-9.5], 3.8% [IC95% 1.1-6.6] and 15.9% [IC95% 10.6-21.3] respectively for STEC, Salmonella spp., C. jejuni and C. coli. Syncerus caffer was established as a potential vehicle of STEC carrying stx1 gene (3.2%), stx2 gene (1.6%) and the combination of stx2 and eae genes (1.6%). On the basis of these data, we suggested the need for developing monitoring plans of the production, preparation, handling and distribution of smoked game meat in Lubumbashi. [less ▲]

The objective of this study was to evaluate the presence of Clostridium difficile in intestinal and carcass samples collected from pigs and cattle at a single slaughterhouse. C. difficile was isolated in ... [more ▼]

The objective of this study was to evaluate the presence of Clostridium difficile in intestinal and carcass samples collected from pigs and cattle at a single slaughterhouse. C. difficile was isolated in 1% and 9.9% of the pig and cattle intestinal contents and in 7.9% and 7% of cattle and pig carcass samples respectively. A total of 19 different PCR-ribotypes were identified, among them types 078 and 014. Seven of 19 ribotypes correlated with the PCR-ribotypes involved in human C. difficile infections in Belgium. This study confirms that animals are carriers of C. difficile at slaughter and ribotypes are identical than those in humans, and that carcass contamination occurs inside the slaughterhouse. [less ▲]

in International Journal of Environmental Research and Public Health (2013), 10

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public ... [more ▼]

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways. A first way is the presence of antibiotic resistant bacteria on food selected by the use of antibiotics during agricultural production. A second route is the possible presence of resistance genes in bacteria that are intentionally added during the processing of food (starter cultures, probiotics, bioconserving microorganisms and bacteriophages). A last way is through cross-contamination with antimicrobial resistant bacteria during food processing. Raw food products can be consumed without having undergone prior processing or preservation and therefore hold a substantial risk for transfer of antimicrobial resistance to humans, as the eventually present resistant bacteria are not killed. As a consequence, transfer of antimicrobial resistance genes between bacteria after ingestion by humans may occur. Under minimal processing or preservation treatment conditions, sublethally damaged or stressed cells can be maintained in the food, inducing antimicrobial resistance build-up and enhancing the risk of resistance transfer. Food processes that kill bacteria in food products, decrease the risk of transmission of antimicrobial resistance. [less ▲]

In the context of the prevailing trend toward more natural products, there seems to be an increasing preference for raw milk consumption as raw milk is associated with several perceived health benefits ... [more ▼]

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in ... [more ▼]

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in Europe. The main objective of this study was to determine the presence of C. difficile in pigs and cattle at the slaughterhouse. C. difficile was isolated in 6.9% of the cattle at the slaughterhouse. None of the pig slaughter samples were positive for C. difficile after an enrichment time of 72 h. For complementary data, a short study was conducted in piglets and calves at farms. C. difficile was more prevalent in piglets (78.3%) than in calves (22.2%) on the farms. Regarding the piglet samples, 27.8% of the positive samples were detected without enrichment of stools. The PCR ribotype 078 was predominant in farm animals. Samples isolated from slaughter cattle presented the widest range in PCR-ribotype variety, and the most prevalent PCR ribotype was 118a UCL. The results of this study confirm that C. difficile is present in slaughter animals in Belgium with a large percentage of toxigenic strains also commonly found in humans. [less ▲]

In 2005, the Belgian authorities reported a Listeria monocytogenes contamination episode in cheese made from raw goat's milk. The presence of an asymptomatic shedder goat in the herd caused this ... [more ▼]

In 2005, the Belgian authorities reported a Listeria monocytogenes contamination episode in cheese made from raw goat's milk. The presence of an asymptomatic shedder goat in the herd caused this contamination. On the basis of data collected at the time of the episode, a retrospective study was performed using an exposure assessment model covering the production chain from the milking of goats up to delivery of cheese to the market. Predictive microbiology models were used to simulate the growth of L. monocytogenes during the cheese process in relation with temperature, pH, and water activity. The model showed significant growth of L. monocytogenes during chilling and storage of the milk collected the day before the cheese production (median increase of 2.2 log CFU/ml) and during the addition of starter and rennet to milk (median increase of 1.2 log CFU/ml). The L. <br /><br />monocytogenes concentration in the fresh unripened cheese was estimated to be 3.8 log CFU/g (median). This result is consistent with the number of L. monocytogenes in the fresh cheese (3.6 log CFU/g) reported during the cheese contamination episode. A variance-based method sensitivity analysis identified the most important factors impacting the cheese contamination, <br /><br />and a scenario analysis then evaluated several options for risk mitigation. Thus, by using quantitative microbial risk assessment tools, this study provides reliable information to identify and control critical steps in a local production chain of cheese made from raw goat's milk. [less ▲]

Food products represent great biotopes for bacteria. The optimization of foodstuffs conservation pass by a better understanding of those biotopes and their spoilage. The current techniques of new ... [more ▼]

Food products represent great biotopes for bacteria. The optimization of foodstuffs conservation pass by a better understanding of those biotopes and their spoilage. The current techniques of new generation sequencing give a new dimension to the microbial ecology, through the metagenomic analysis of individuals' large number, within a mixed microbial population. Our aim is to demonstrate that this methodology can be successfully applied to the validation of the quality of foodstuffs during storage. This study was carried out on pork minced meat with shelf-life tests in various conditions of preservation (temperature and packaging). The analysis was performed in parallel with standardized microbiological methods and with massive sequencing of two hypervariables regions of the rDNA 16S. The results show an excellent correlation between the two approaches and underline the tremendous utility of metagenomic analysis for in-depth characterization of the potential altering bacteria in fresh meat. [less ▲]

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial ... [more ▼]

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial stability and the safety of these products. In this context, the aim of this study was to isolate and characterize Carnobacterium from long shelf-life vacuum-packed beef. LAB counts after culture at +22°C remained below 2.0 log UFC/cm², even at the end of shelf life. On the other hand, the ecosystem evaluation performed by metagenomics revealed the predominance of Carnobacterium and Lactobacillus on the samples. After spreading of a peptone water suspension obtained from the samples on PCA, pure isolates were collected and identified by API 50 CHL galleries. Seventy-eight % of isolates were C. maltaromaticum, 3 % C. divergens and 19 % could not be identified. The next step of this work will consist in performing a genotypic and functional characterization of these Carnobacterium isolates. [less ▲]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. This work describes the application of this technique to study the bacterial population of two ... [more ▼]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. This work describes the application of this technique to study the bacterial population of two fresh fish filets. The two fish species are from freshwater (pangasius) and seawater (haddock), respectively. Samples where directly analyzed the day of receipt. Others samples were analyzed at the end their shelf life after storage at 4°C (1/3 of their shelf life) and 8°C (2/3 of their shelf life). For these samples, packagings were made in plastic wrap for atmospheric air condition and in trays under modified atmosphere. Classical microbiological and 16S rDNA metagenomic analysis were carried out on all these samples. The composition and evolution of microbial populations of fish filet stored under different packaging conditions and temperatures of storage were investigated with identification of bacteria species. A total of 40 different species were identified for both fish types. Gram-negative bacteria are always predominated among the initial flora and at the end of the shelf life in all the trials. At the beginning of storage, the predominant Gram-negative microflora consisted of Moraxellaceae (Acinetobacter spp, Psychrobacter spp.), Pseudomonadaceae (Pseudomonas spp), and Shewanella spp and the Gram-positive flora was identified as Lactobacillaceae (Carnobacterium spp), Brochothrix thermosphacta and Planococcus donghaensis (only for pangasius). For the pangasius, Planococcus donghaensis is only present before the fish is packed and its dominant presence could provide an indication of the freshness of the fish. The metagenomic analysis is a useful tool to identify and to measure the relative proportions of bacterial species in fish filet samples. [less ▲]

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen ... [more ▼]

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen atmosphere. VP striploins from bulls (B) and cows (C) were stored at −1 °C and +4 °C for up to 80 days. These meats were subsequently repackaged under modified atmosphere (MA) – 70 % O2/30 % CO2 – at different times, and stored 2 d at +4 °C and 5 d at +8 °C. The average initial counts in VP meats were 3.6 log CFU/cm² (B) and 2.7 log CFU/cm² (C) for total viable count (TVC) at +22 °C; < 2.0 log CFU/cm² (B and C) for lactic ac id bacteria (LAB) at +22 °C; 1.1 log CFU/cm² (B) and 1.3 log CFU/cm² (C) for Enterobacteriaceae at +30 °C and < 1.0 log CFU/cm² (B and C) for Pseudomonas spp. and Brochothrix thermosphacta. During the first 40 days of VP storage, temperature had a striking influence on microbial growth. The maximum count differences between storage temperatures were obtained at the 20th day of storage: 2.7 log CFU/cm² (B) and 2.9 log CFU/cm² (C) for TVC, 4.0 log CFU/cm² (B and C) for LAB and 3.6 log CFU/cm² (B and C) for Enterobacteriaceae. The difference in TVC between temperatures at the 20th day tended to disappear once the meats were repacked under MA and stored during seven days. Conversely, the difference in LAB and Enterobacteriaceae counts tended to be maintained after MA repackaging, showing that duration and temperature of VP storage had influence on microbiological quality of BB meat subsequently stored in high-oxygen atmosphere. Moreover, chilling at temperatures very close to the freezing point of meat during VP storage, which has already showed innumerous advantages for physicochemical quality of meat, was capital to maintain the microbiological quality of BB fresh meat during subsequent MA-packed storage. [less ▲]

Metagenomic analysis is a new culture-independent approach for assigning a taxonomic, genic or functional identity to bacterial DNA fragments of unknown origin. Its power and utility is increasingly ... [more ▼]

Metagenomic analysis is a new culture-independent approach for assigning a taxonomic, genic or functional identity to bacterial DNA fragments of unknown origin. Its power and utility is increasingly rising thanks to the next generation sequencing techniques. It is now mature and cheap enough to be transposed to more applied fields like the food microbiology. We demonstrated in several studies the extraordinary potential of the targeted metagenomic analysis to different problematics related to food products. First, this approach is highly useful for the validation of the shelf life of food products. We analyzed standardized pork minced meat and meat product samples packaged either under modified atmosphere (MAP - 30% CO2, 70% O2) or under permeable atmosphere packaging, stored at different temperature (4°C, 4-8°C and 12°C) until the end of shelf-life. The metagenomic analysis allowed to identify species of all the sub-dominant bacterial populations. This approach showed why MAP can improve meat quality by favoring certain species rather than others. As a second example, we sought to identify the potential spoiling bacteria in several food products like raw fish, rind cheese or vacuum packed beef meats in order to illustrate the usefulness of metagenomics for the quality control of food preparations. Samples from various food matrices were screened to identify the bacterial contaminants. We combined the bioinformatics analysis with a classical approach to generate effective quantitative data for the various bacterial populations detected. This analysis characterizes the samples both on the identity of the potential spoiling bacteria present and on the quantification level of the contaminants. Finally, the metagenomic analysis reveals the presence of numerous uncultured and uncharacterized bacteria. The use of a carefully designed analysis pipeline has been used to ensure to label the bacterial population with a precise taxonomic identity and to determine whether the targeted population corresponds to a known species or not. This way, even if the nearest known homologous sequence is an environmental sample, its relatedness to known species can be deduced. This represents a new tool to trace yet uncharacterized food spoiling bacteria. [less ▲]

Steak tartare is a popular meat dish in Belgium and other european countries. It is often consumed with french fries or as sandwich spread. This product, due to its raw nature, is highly sensitive to ... [more ▼]

Steak tartare is a popular meat dish in Belgium and other european countries. It is often consumed with french fries or as sandwich spread. This product, due to its raw nature, is highly sensitive to bacterial alteration. A better understanding of the bacterial content of this meat product will thus be insightful to master the alteration hazards. Throughout a targeted metagenomic analysis we characterized the bacterial populations of several steak tartare samples. These samples were bought and analyzed during the same day, from three different commercial sources: butchery, sandwich vendor and restaurant. A classic microbiological analysis was performed in parallel. The metagenomic analysis was targeted on two different hypervariable regions of the bacterial 16S rDNA, in order to compare the bacterial identification efficiency. A total of 60,500 sequences for 12 samples were submitted to a metagenomic analysis. The best hypervariable region enabled us to identify 356 different bacterial species. Lactobacillus algidus is the leading bacterial species, representing 52% of the total analyzed sequences, followed by an uncultured Pseudomonas sp. (8.43%) and Photobacterium phosphoreum (7.92%). The analysis of the results shows that remarkable differences appear between the three sources of steak tartare. First, the samples from the butchery are mainly composed of Lactobacillus populations and to a lesser extend of environmental contaminants like Xanthomonas campestris. On the opposite, the samples from the restaurant are contaminated with higher level of Leuconostocaceae like Leuconostoc carnosum or an uncultured Weissella sp., or with gamma-proteobacteria like Pseudomonas sp. or Psychrobacter sp. These last samples were characterized with some alteration (slime, off odor) that can thus be put in relation with the bacterial populations identified. Combining a broad-range sequencing effort to a rigorous computer analysis gives a powerful tool for the microbiology of food products. Its application can be virtually extended to every food product be readily transposed to the food industry. [less ▲]

Among the culture-independent techniques, ultra-sequencing has contributed to place metagenomic analysis as the best alternative to study complex microbiota. During the last three years, metagenomic ... [more ▼]

Among the culture-independent techniques, ultra-sequencing has contributed to place metagenomic analysis as the best alternative to study complex microbiota. During the last three years, metagenomic studies were used essentially for environmental samples but it could be used also to analyse bacterial populations of food samples. This work describes the application of this technique to study the bacterial population of different types of soft cheeses. Among these, three of them are a typical Belgian soft cheese with washed rind (two with raw milk and the third with pasteurized milk). The fourth is a French creamy soft cheese made with raw milk. Classical microbiological and 16S rDNA metagenomic analysis were carried out in the core and on the rind of the four cheeses, giving a total of 8 samples. In total, 48 genus and 163 species were identified for all samples. As expected Lactoccocus lactis and/or cremoris are the most representative species in the core of the four cheeses. On the rind of cheeses, the predominant bacterial species are Psychrobacter glacinola, Staphylococcus equorum, Corynebacterium casei and Marinilactibacillus psychrotolerans. Brevibacterium spp and Psychroflexus spp are important for the rind of washed rind cheeses. All these species are present in different proportions following the origin and the cheese making process and they are well known for their organoleptic properties on the rind of cheese. The two Belgian soft cheese made with raw milk are composed of many more different bacterial species. While the cheese made from pasteurized milk contains less species mainly composed by Lactococcus lactis (97,6%) in the core. An unexpected result is the low diversity of the a French creamy soft cheese made with raw milk with only two predominent species : Lactoccocus cremoris and Leuconostoc citreum are present in the core (94,9% and 4,9% , respectively) and on the rind (93,8% and 5% , respectively). Compared with the other cheeses made with raw milk, this result is surprising. The bacterial cheese microbiota plays a central role in cheese-making. The subtleties of cheese character, as well as their shelf-life, are largely determined by the evolution of their microbiota. [less ▲]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. Its interest has started to appear in food microbiology but only on the study of very ... [more ▼]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. Its interest has started to appear in food microbiology but only on the study of very particular bacterial populations of fermented food. This work describes the application of this technique to study the bacterial population of two fresh fish filets. The two fish species are from freshwater (pangasius) and seawater (haddock), respectively. Samples where directly analyzed the day of receipt. Others samples were analyzed at the end their shelf life after storage at 4°C (1/3 of their shelf life) and 8°C (2/3 of their shelf life). For these samples, packagings were made in plastic wrap for atmospheric air condition and in trays under modified atmosphere. Classical microbiological and 16S rDNA metagenomic analysis were carried out on all these samples. The composition and evolution of microbial populations of fish filet stored under different packaging conditions and temperatures of storage were investigated with identification of bacteria species. A total of 40 different species were identified for both fish types. Gram-negative bacteria are always predominated among the initial flora and at the end of the shelf life in all the trials. At the beginning of storage, the predominant Gram-negative microflora consisted of Moraxellaceae (Acinetobacter spp, Psychrobacter spp.), Pseudomonadaceae (Pseudomonas spp), and Shewanella spp and the Gram-positive flora was identified as Lactobacillaceae (Carnobacterium spp), Brochothrix thermosphacta and Planococcus donghaensis (only for pangasius). Regardless the packaging and the fish origin, significant variations of the initial flora were noted. The important growth of some Gram negative populations could indicate a risk of spoilage. Thus, the metagenomic approach could be used to adequately determine the duration of shelf-life. For the pangasius, Planococcus donghaensis is only present before the fish is packed and its dominant presence could provide an indication of the freshness of the fish. The metagenomic analysis is a useful tool to identify and to measure the relative proportions of bacterial species in fish filet samples. [less ▲]

Predictive microbiology aims to predict the evolution of microorganisms in foods with mathematical models. Several models have been published and the complexity of some of them makes their use difficult ... [more ▼]

Predictive microbiology aims to predict the evolution of microorganisms in foods with mathematical models. Several models have been published and the complexity of some of them makes their use difficult for the uninitiated. However, the use of this discipline will become widespread in coming years. These models provide, for example, additional tools to ensure the microbiological safety of food, to establish the contamination flow in a food chain, to develop and to assist the quality assurance systems. The development of new computer software and database will enable stakeholders in the food chain to have a better control of microbiological hazards. The aim of this summary is to give an overview of existing models of predictive microbiology and their applications. A first approach of the primary, secondary and tertiary models is given. The modelling of latency, integrated models and growth tests are also discussed. [less ▲]

Introduction: Food products represent great biotopes for bacteria. The optimisation of foodstuffs conservation, mattering so economically as from the point of view of the public health, pass by a better ... [more ▼]

Introduction: Food products represent great biotopes for bacteria. The optimisation of foodstuffs conservation, mattering so economically as from the point of view of the public health, pass by a better understanding of those biotopes and their spoilage. Microbiologists had already tried to resolve this problem throughout several approaches. Studies based on classical microbiology cultures were completed by strategies centred on approaches independent from the microbiological culture. Purpose: The current techniques of new generation sequencing give a new dimension to the microbial ecology, through the metagenomic analysis of individuals' large number, within a mixed microbial population. Our aim is to demonstrate that this methodology can be successfully applied to the study of foodstuffs microbial flora, and can be adapted to the specific requirements of food microbiology. Methods: This study was carried out on pork's minced meat and white sausage, with shelf-life tests in various conditions of preservation (temperature and packaging). The rDNA 16S was extracted from the original products and samples in the best-before date and, after standardization, hypervariable regions V5 were sequenced. Results: A total about 130.000 sequences were obtained and a metagenomic analysis succeeded in the taxonomic classification to the genus level for 80 % of this population. The subsequent analysis of microbial populations shows that the majority microbial populations at the expiration date are the same ones which are generally observed during microbiological analysis of these meat products. However, the population subdominants and especially several populations of not cultivable germs were able to be identified. These groups of bacteria, more difficult to obtain by the other methods, must be studied because they participate in the spoilage process of food products. Significance: The sensibility of this technology makes possible the analysis of foodstuffs presenting a very low microbial rate and, thus, allows the identification of the microbial contaminants before they grow the levels detected by cultural methods. [less ▲]